So if good bacteria lives on the rocks,,gravel and other decor. If i was to take one of the filters, a bunch of gravel, and some of my rock ledge from my tank and put it into my new tank. Also take 40% of the water from my one tank. Would the tank be cycled or no? It might be a stupid question but it kinda seems like t would work. Also I'm only gonna put 4 gold barbs in off the start if it does seem like it will work.
Anyways what do you guys think of the idea? I'm sure someone has tries it.

So if good bacteria lives on the rocks,,gravel and other decor. If i was to take one of the filters, a bunch of gravel, and some of my rock ledge from my tank and put it into my new tank. Also take 40% of the water from my one tank. Would the tank be cycled or no? It might be a stupid question but it kinda seems like t would work. Also I'm only gonna put 4 gold barbs in off the start if it does seem like it will work.
Anyways what do you guys think of the idea? I'm sure someone has tries it.

Ya, that's the best way to do it, but, me being the OCD over-cautious person i am... i'd cycle it just to be safe. You could probably get away with it though. Also, how big is the upgrade?

Yep, that's exactly how I start up my QT, more or less. A fully cycled filter, 50% tank water and 50% cured water is just like doing a 50% water change. The decco and gravel will only add to the bacteria count. I've put fish in minutes after using this method with no ill effects what so ever, but a 24hr period to let the tank settle in (as it were) won't hurt.

Just keep in mind that, the tank losing the filter (decco/gravel) could experience a bloom/mini cycle unless it's over filtrated.

Nope I put 4 gold barbs in for a day then the other three. Now I was just waiting to see how the levels played out. Nitrate is at 5 ppm it was probably around 2 when I set it up. The other tank was at 20 and I took about 45% of the water from it and it was around 5 ppm after. It filled the other tank up around 25% of the way